1. Field of the Invention
The present invention relates to a portable terminal, and more particularly to a sliding-type portable terminal having a pair of housings coupled to each other while being able to slide with request to each other.
2. Description of the Related Art
In general, portable terminals are basically used for mobile communication. However, recent portable terminals can provide not only conventional mobile communication, but also various types of services including multimedia services (e.g. playing music and moving picture files) and financial services (e.g. micro payment, mobile banking).
Portable terminals are classified into bar-type terminals, flip-type terminals, and folder-type terminals according to their appearance. In addition, sliding-type terminals have recently appeared and, together with folder-type terminals, occupy a dominant position in the portable terminal market.
Bar-type terminals have an input/output device (e.g. keypad, transmitter), a display device, and an output device (e.g. receiver), all of which are positioned on a single housing. Although the bar-type terminals have an advantage of simple construction, the fact that a distance must be secured between the transmitter and the receiver for voice communication adversely affects their compactness.
Flip-type terminals have a bar-type body and a flip cover rotatably mounted on the body. Although the flip-type terminals are advantageous in that their input device (e.g. keypad) is covered in a standby mode so as to avoid erroneous operations, the fact that a distance must be secured between their transmitter and receiver for voice communication adversely affects their compactness, as in the case of the bar-type terminals.
Folder-type terminals have a pair of housings coupled to each other so as to fold on and unfold from each other, as well as voice input and output devices positioned on different housings. Such construction easily secures a distance between the transmitter and receiver without degrading the compactness. Therefore, the folder-type terminals have been dominant in the portable terminal market for a long period of time.
Sliding-type terminals have a pair of housings coupled to each other so that they can slide relative to each other, as well as voice input and output devices positioned on different housings. Input device, e.g. the keypad, is adapted to be exposed/covered as the housings slide relative to each other. Therefore, erroneous operations are avoided in a standby mode, and a distance is easily secured between the voice input and output devices in a communication mode without degrading the compactness. For these reasons, the sliding-type terminals have overtaken the folder-type terminals in the market.
Particularly, sliding-type portable terminals have sliding members mounted on their main body and sub-body which are coupled to each other while being able to slide. However, conventional sliding-type portable terminals have a problem in that it is not easy to prevent the sub-body from playing with regard to the main body while maintaining smooth upward/downward sliding movements of the bodies. More specifically, if the play of the sub-body in the forward/rearward or leftward/rightward direction relative to the main body is reduced, the increased frictional force adversely affects the upward/downward sliding movements. If the frictional force is reduced for smooth sliding movements, play in the forward/rearward or leftward/rightward direction inevitably increases.